Hello

I have questions about this topic...In my company, people usually use design temperature as an ope case,so caesar calculate Sh (and Sa of course) with this one.

This design case isn`t the max operation case so we're oversizing the calculation. This I think is not a problem but i think it should be different...can we change how caesar calculate Sh, taking for example T2 insted of Tdesign?

The second doubt is about load cases. In my company it is usual to consider for design temp:

L1:OPE(design):W+P2+T2
L2:SUS(DESIGN): W+P2
EXP:L1-L2

I think this is a mistake because the probability to this temp for this system is almost zero. Maybe if we can use F>1 for the names of cycles...what do u think?

You can use the [Search] facility in this Forum to find previous posts on this topic.

As of CAESAR II V.6.10, you can specify which Sh you want the SUSTAINED case compared to.

I know that there's a search tool in this forum... but i didnt find anything that can answer my doubts.

So, anyone can help me with my 2 doubts??

THANK YOU VERY MUCH

if you dont want to compare your sustain stress with design (Short term ) temperature allowable ,make separate file for your short term case and check only expansion stress

Thank you... I surrender in that case...I'll wait for the next Caesar.

But, anyone can help me with my other doubt?How to consider the design temperature?
Thank you

I'll assume you are using the current edition of B31.3. And it looks like you are interested in evaluating longitudinal stress due to sustained loads.
These stresses are limited by system collapse. If the system can get to a higher temperature than the limit should be the (lower) basic allowable stress (Sh) at that higher temperature - even if it is a temporary temperature rise.
If I guessed wrong, please restate your question providing more details.
(If it's a language issue, perhaps someone can respond to your question if you restate it in Spanish.)

hi..hi ok iam really sorry.. this is the only one fair solution in caesar current version..u can wait till next next version

We're using B31.1.I'm really sorry about my english, I've written quickly and I asume that I have many mistakes.

My first doubt: Sh is calculated using the higher temperature you put in Caesar. Ok, I dont know why but, as you say in your answer there will be changes in the next version.

The other doubt/question is about load cases. In my company, we use a temperature, called " design temperature" that we know we never get it in a pipe. So that, I consider that I'm oversizing the calculation because the only one way to evaluate with this temperature is with EXP case, where we take at least N=1 in fatigue cycles.

How can we consider design temperature an occasional load that we perhaps get few times...or never?

I dont know other way to explain...

I'd have no problem translating in Spanish but I think the question has already been answered above.

Really, this Sh issue is a non-issue. We should make our calculations as conservative as possible and using the Design Temperature to get the Sh is good enough for me. This would only be a big problem in hot systems where the design temperature actually reaches the derated values of the material's allowable stress and where the operating temperature is far below (and if the difference is significant enough to cause schedule change).

But otherwise, the stresses should be checked at the Design Sh because the system is technically allowed to operate that hot. Twenty years down the road someone could choose to increase the operating temperature and then your philosophy would be invalid.